This invention relates to clamping mechanisms and in particular to clamp mechanisms for the attachment of electronic modules to racks used in industrial and military applications.
Numerous electronic control devices are typically carried aboard airplanes, large ships and in some military vehicles. The usual mounting for such devices is by rack mounting, wherein the individual electronic units are mounted side by side or in a vertical arrangement in an enclosure having means to provide mechanical moorings for the units. Older methods for installing such devices in the rack included the use of flanges mounted on the front face of the individual electronic units which could be bolted to flanges on the rack. Later devices provided clamping apparatus on the rack which captured a flange formed on the front of the individual units to retain the units to the rack.
With the establishment of standardized electronic module size specifications has come the need for channel engaging clamps for mechanical retention of the unit or module to the rack. In this type of arrangement, the rack is provided with channels extending into its enclosure on both the top and bottom.
In one apparatus from the prior art, wedge clamps having a series of wedge shaped elements and having a single screw passing therethrough have been utilized to mount printed circuit boards in a rack having a single channel. This form of existing wedge clamp, when relaxed, features a generally aligned series of wedges, each centrally mounted on a single screw and interacting with a wedge shaped element mounted to the printed circuit board to be mounted. The relaxed wedge clamp may be inserted into the channel of the rack. When in place, the screw is tightened, causing a shortening of the effective length of the clamp and a consequent transverse displacement of the wedges from their relaxed aligned position. This displacement causes a widening of the effective width of the clamp, thereby creating rigidity with the rack's channels. This type of simple wedge has been considered for use with encased standardized electronic modules. This type of two directional wedge clamp is satisfactory for mounting of low mass units which require a single wedge clamp on opposing sides of the modules but for those modules or units where additional clamps are required due to the increased widths of the units, a stack up of tolerance variations between the channels of the rack and the fixed element of the two directional wedge clamp renders the two directional clamp inoperable.